Geology 



its advantages, as it enabled us to make a fuller and 

 more detailed survey. The structure of the country now 

 became very complicated. Lofty mountains towered on 

 either hand, the dip of the strata was very steep, and 

 the rocks were frequently cleaved and crumpled. 



The Trias, as on the south side of the plain, rested 

 unconformably on rocks of Silurian age, in this instance 

 a grey slaty rock with very few fossils. The dip was 

 now towards the south, and varied from 50 to 80. 

 Sections were plentiful in the rugged country, which fact 

 alone rendered possible the unravelling of the complex 

 structures. 



The Silurian slates were found to be resting upon 

 grey grits with Ordovician fossils the Ordovician was 

 the oldest formation we had yet encountered, and it 

 was followed by other beds which from the presence of 

 trilobites of the genus Paradoxides we concluded to be 

 Cambrian, the oldest fossiliferous series. 



The dip of the rocks increased in steepness as we 

 ascended the valley, and in the Cambrian outcrop reached 

 60. The bedding of the Cambrian rocks was rather 

 confused, but there appeared to be an anticlinal fold 

 near the middle of the outcrop. 



Following the stream, we again reached Ordovician 

 rocks, but the dip still appeared to be towards the south, 

 and in one section the Cambrian beds could be seen 

 resting on the Ordovician. This was clearly a case of 

 inversion of the beds caused by over-folding as seen in 

 Fig. 30. The Ordovicians were found to rest upon 

 Silurians a little farther up stream, a fact which confirmed 

 the view that the rocks were over-folded. 



In the Silurian outcrop there was a reversed fault, 



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